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/*******************************************************************************
* Copyright (c) 2009, 2010 Cloudsmith Inc. and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Cloudsmith Inc. - initial API and implementation
*******************************************************************************/
package org.eclipse.equinox.internal.p2.metadata.expression;
import java.util.*;
import org.eclipse.equinox.p2.metadata.IVersionedId;
import org.eclipse.equinox.p2.metadata.expression.IEvaluationContext;
/**
* An expression that is especially targeted towards {@link IVersionedId} instances. It will
* reject any objects that is not an <code>IVersionedId</code> and it will ensure that the
* resulting iterator only iterates over the latest version of any found id.
*/
final class Latest extends UnaryCollectionFilter {
Latest(Expression collection) {
super(collection);
}
public Iterator<?> evaluateAsIterator(IEvaluationContext context) {
HashMap<String, IVersionedId> greatestIUVersion;
if (operand instanceof Select) {
// Inline element evaluation here so that we don't build a map that is
// larger then it has to be
Select select = (Select) operand;
Iterator<?> iterator = select.operand.evaluateAsIterator(context);
if (!iterator.hasNext())
return Collections.EMPTY_SET.iterator();
greatestIUVersion = new HashMap<String, IVersionedId>();
LambdaExpression lambda = select.lambda;
context = lambda.prolog(context);
Variable variable = lambda.getItemVariable();
while (iterator.hasNext()) {
Object next = iterator.next();
if (!(next instanceof IVersionedId))
continue;
variable.setValue(context, next);
if (lambda.evaluate(context) != Boolean.TRUE)
continue;
IVersionedId versionedID = (IVersionedId) next;
String id = versionedID.getId();
IVersionedId prev = greatestIUVersion.put(id, versionedID);
if (prev == null)
continue;
if (prev.getVersion().compareTo(versionedID.getVersion()) > 0)
greatestIUVersion.put(id, prev);
}
} else {
Iterator<?> iterator = operand.evaluateAsIterator(context);
if (iterator == null)
return null;
if (!iterator.hasNext())
return Collections.EMPTY_SET.iterator();
greatestIUVersion = new HashMap<String, IVersionedId>();
while (iterator.hasNext()) {
Object next = iterator.next();
if (!(next instanceof IVersionedId))
continue;
IVersionedId versionedID = (IVersionedId) next;
String id = versionedID.getId();
IVersionedId prev = greatestIUVersion.put(id, versionedID);
if (prev == null)
continue;
if (prev.getVersion().compareTo(versionedID.getVersion()) > 0)
greatestIUVersion.put(id, prev);
}
}
return greatestIUVersion.values().iterator();
}
public int getExpressionType() {
return TYPE_LATEST;
}
public String getOperator() {
return IExpressionConstants.KEYWORD_LATEST;
}
}
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